Liquid injectable oil-pectin-drug therapeutic compositions



Patented Dec. 20, 1949 LIQUID INJECTABLE OIL-PECTIN-DRUG THERAPEUTICCOMPOSITIONS Henry WelclnSilver Spring, Md., assignor to the UnitedStates of America No Drawing. Application June 3, 1947. Serial No.752,298

8 Claims. '(01. 167-58) v (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0.

, My invention relates to therapeutic products and more particularly toinjectable therapeutic products wherein it is desirable or necessary toprolong their therapeutic activity in the animal body.

In the administration of penicillin or in other mold or bacterialexcretory or metabolic products, it has been the standard practice toinject an aqueous solution of the substance subcutaneously orintramuscularly. Penicillin in aqueous solution is, however, rapidlyabsorbed into the blood stream and probably reaches a maximumconcentration in the body within fifteen minutes after injection.Following a single intramuscular injection 10,000 to 30,000 units), theconcentration of penicillin in the blood rapidly diminishes due to rapidabsorption and excretion from the body and is practically zero withintwo to three hours after injection. This necessitates frequent aqueouspenicillin injections intramus cularly to the discomfort and even harmof the patient who may have to be awakened every few hours during thenight for such treatments.

Accordingly, many expediencies have been proposed directed to the end ofmaintaining an effective therapeutic penicillin blood levelconcentration for a prolonged period of time. These include continuousintravenous injections, continuous intramuscular administrations, theestablishment of an excretory blockade in the patient by thesimultaneous administration of paraaminohippuric acid or diodrast andthe use 01' ice packs at the site of intramuscular injection.Prolongation of therapeutic activity has also been attempted withvarious slowly absorbed vehicles,

billty in tissue fluids), beeswax is absorbed with great difllculty bythe human body requiring on an average from twenty-five to thirty daysto be assimilated by the body. Furthermore, sterile abscesses arefrequently formed by beeswax preparations and moreover are painful atthe site of injection for prolonged periods. There is, therefore, needfor a preparation which will prolong the activity of penicillin in thebody while avoiding the disadvantages of the beeswax preparation.

For example, a preparation of beeswax, penicillin and oil, because ofthe beeswax content is very slowly absorbed by the body due to theinability of the animal tissue to digest and assimilate beeswax from thesite of injection. By contrast, and at the other extreme, a solution ofsucrose (a polysaccharide), penicillin and water is very rapidlyabsorbed by the body and no prolonged effect of penicillin is securedsince sucrose is readily digested and 'absorbed by the body along withthe penicillin from the site of injecsuch as, peanut oil and beeswax,globin and the like.

With certain of these vehicles, such as globin and the like, prolongedaction of penicillin in the blood is not obtained to a sufficientdegree.

The development of penicillin in oil and wax overcame the rapidabsorption of penicillin but manifested other disadvantages. Whenpenicillin is suspended as a dry salt (e. g. calcium salt) in oil withbeeswax and injected into the body a mass is formed in the tissues,consisting of beeswax in which penicillin is entrapped. Water from thetissues gradually dissolves out the peni cillin from this beeswax matrixand in a matter of 20 to 24 hours the penicillin has been completelyabsorbed, although the beeswax itself remains for some time in thetissue.

Beeswax is a well-known sensitizer and thus produces allergic reactionswhen injected into the body in combination with peanut oil andpenicillin. Because of its structure (1. e. insolution. In between thesetwo extremes there are certain hydrophilic substances which may besubstituted for the beeswax and sucrose and which are digested andassimilated by the body. However, because of their colloidal gel-likestructure formed on contact with water in the body tissues, they entrapand then slowly release a drug such as penicillin from a repository sitein the tissues. Such colloidal gels are not readily absorbed as issucrose but still are not inordinately delayed in their absorption as istrue of beeswax.

Thus, a desirable preparation for prolonging the activity of penicillinin the body would be one that is readily absorbed and assimilated by thebody, that is not in aqueous solution, that does not form sterileabscesses on injection, and that does not sensitize the individualinjected, and finally that forms a repository site from which thepenicillin is gradually released following contact with the wateryfluids of the tissue.

Stated briefly, then a substance that could be suspended in a dry statein an injectib'le vegetable oil, that is in nature hydrophilic, that isreadily absorbed by the body yet entraps a drug such as penicillin inits colloidal gel matrix and slowly releases it would be a suitablesubstance for prolonging the action of the drug.

Examples of such classes of substances are polysaccharides such aspectin, sodium alginate, and certain dextrins, and cellulose compoundsall of which are of the group which form gels on contact with waterincluding protein substances such as gelatin.

Although in the above I have referred to this problem with respect topenicillin, it is also a problem in other therapeutic products includingsuch antibiotics as streptomycin and bacitracin; in insulin therapy; inhormone therapy; in vast)- constrictor therapy and indeed in the use ofany injectable drug where it is desired to prolong the therapeuticaction of the drug over a relatively long period of time.

It has already been noted that if this drug to be used is, in its, drystate, mixed with an agent which on contact with the fluids of the bodyforms a colloidal gel holding the drug in suspension, the period ofabsorption of the drug by the body will be extended, particularly wherethe agent is itself absorbed by the body in substantially the sameperiod of time.

Accordingly, an object of my invention is to provide a novel therapeuticproduct comprising a drug in such form that its absorption by the bodytion of active material.

Still a further object is to provide a therapeutic productwhich will notcause the development of sensitization in human beings and one which isreadily absorbed and assimilated by the patient.

In general, in accordance with my invention, I suspend the desired drugwith a hydrophilic agent such as a polysaccharide, including by way ofexample, pectin, sodium alginate and certain dextrins; or with cellulosecompounds; or with certain protein substances such as gelatin. All ofthese agents are so selected that they have the common and hereessential characteristic that they form collodial gels on contact withthe The colloidal gels entrap the'drug in the gel matrix and slowlyrelease it while being itself absorbed by the body for which it has aninfinity. r I

In carrying out my invention, I suspend the drug and the selected agentin an injectable oil such as vegetable oil which also has an infinityfor body tissue, 1. e. is readily absorbed thereby. Such oils by way ofexample are peanut oil, sesame oil, cottonseed oil, corn oil, soy beanoil,

-etc.; or I may use such injectable glycols as tassium penicillin G(1500 units per milligram) having an average particle size of the orderof from 50 to 100 microns. Two hundred and seventy milligrams of thispectin is mixed with 180 milligrams of the crystalline potassium peni-Ycillin G and to this mix there is added suflicient peanut oil oi thetype described in U. S. P. 13

(highly refined) to make a total of one milliliter.

The preparation is then mixed thoroughly in a Waring Blendor until it ishomogeneous.

The individual ingredients are-preferably steriof the type describedabove and 180 milligrams of crystalline penicillin, or 67.5 milligramsof the pectin described plus 180 milligrams of the crystallinepenicillin. In each of the latter examples peanut oil of the typedescribed above is added to make up one milliliter.

Becauseof the hydrophilic nature of the product it is advisable tocarryout the manufacturing steps described above under conditions wherethe product will not absorb moisture, as for example,

in an air-conditioning room. Although in the above a particle size hasbeen specified for desirable results, it should be understood that otherranges of particle sizes depending upon the desired therapeuticproperties may be employed. The product described above may beadministered directly in this form to the patient undergoing penicillintherapy.

Attached hereto are a series of tables showing experimental resultsusing this novel drug. Table I presents data secured employing a productmade as described above of crystalline potassium penis cillin G, refinedpeanut oil, and National Formulary VIII pectin following the injectionintramuscularly of approximately 250,000 units and 270 milligrams ofpectin. Fifteen patients were utilized in this series. Relatively highblood levels of penicillin were obtained in the 12th andl6th hours andthe blood levels obtained up to the 24th hour are comparableto thoseobtained with penicillin in oil and wax. It will be noted that themajority of patients maintained for twentyfour hours a blood level of.03 unit of penicillin which is a therapeutically effectivebloodconcentration of this drug.

In Table 2 results secured from the injection of a number of rabbits ofequal weight with 1 cc. of pectin penicillinv in oil mixture made inaccordance wtih this invention is shown. As a' control, rabbits weresimilarly injected with 1 cc. of Romansky Formula VIII (300,000 units)(penicillin, beeswax and oil control) Blood levels were taken at onehour and at 24 hours as set forth in the tables.

TABLE 1 Penicillin blood levels following single intramuscular infectionof 250,000 units of penicillinpectin Units of Penicillin per Milliliterof Serum Name 12 Hr. 16 Br. 20 Hr. 24 Br.

0. 0. 064 0. O6 0. 03 0. 5 (l. 25 0. 03 0. 06 0. 5 I. 0 0. 5 0. 0 l. 0l. 0 0. 03 0. 1% 0. 0G 0. 06 0. 06 0. 06 l. 0 l. 0 I O. 06 0. 0 0. 03 0.03 0. 03 0. 03 0. 03 O. 03 0. 03 0. 03 0. 0G 0. 06 0. 06 0. 06 0. 0G 0.125 0. 0 0. 0 2. 0 1. 0 0. 03 03 0. 5 0. 03 0. 03 O. 06 0.05 0.03 0.03.0.0 l. 0 1. 0 0. 0 0. 0 l. O 1. 0 0. 06 0. 03

l ampuic only inJected.

Rabbit Peanut Oil Beeswax. Control It will be noted that high penicillinlevels were obtained on all rabbits tested with the pectin preparationone hour after injection and except for two rabbits, all showed bloodlevels of penicillin in the 24th hours. The two that failed todemonstrate twenty-four levels received a preparation containing only165,000 units per cc.

In the injection in all of the above cases, I found that the pectinpreparation (270 or 135 mg./cc. type) could not be packaged in multipledose vials. This preparation must be put up in cartridges which utilizerubber stoppers as plungers. When the pectin preparation is drawn upinto the syringe using glass plungers the plunger invariably binds as itis pushed in the barrel.

' This apparently is due to the jelly-like nature of pectin which, underthe pressure of the glass plunger, creates a sticky substance betweenthe plunger and the walls of the syringe causing it to freeze thereon. Ihave found, however, that the flexibility of the rubber plungerovercomes this difllculty during injection.

Summarizing the invention, it will now be clear that the formation of acolloidal gel entrapping penicillin outside the body which conditionwould be obtained from mixing pectin, penicillin and water results in apreparation that is not eilicacious in prolonging the activity ofpenicillin in the body. This may be explained by the fact that in itsaqueous condition the absorption of the drug in the body is rapid and isnot prolonged.

If the colloidal gel is formed outside the body by the addition ofwater, the penicillin being hydrophilic immediately goes into solutionand thus on injection acts, for all practical purposes, like aqueoussolutions of penicillin which are, as is well known, rapidly absorbedand consequently rapidly excreted from the body.

It is therefore essential to this invention that the pectin inpenicillin mix should contain less than 1.0% of water at the time ofpreparation and that this mixture in turn be suspended in an injectlblevegetable oil also containing less than 1% water so that the gel is notformed prior to the injection to the body but rather that the gel isformed only after injection and only as the preparation comes in contactwith the body fluid.

I ofler as an explanation of the prolonged action of penicillin, pectinand oil preparations made in accordance with my invention, that becausewhen it is injected with a minimum moisture content (in the so-calleddry state), a repository site is formed in the tissue. As the water bodyfluids come in contact with the pectin, a colloidal gel is formed.Inasmuch as this contact is, however, inhibited to some degree by theoil which is hydrophobic, the penicillin which has been entrapped in thecolloidal gel is only slowly released from the repository site at a ratedetermined by the tissue fluids ability to reach. the penicillin.

It may be considered that the penicillin at the outer edges of therepository site is relatively rapidly absorbed since it is in contactwith the body fluids almost at once. The early relatively highbloodlevels of the drug which are obtained on injection into both animal andman are explainable on this basis. The delayed absorption and prolongedlevels of the drug, 1. e., the penicillin demonstrable in the injectedindividual in the 20th-24th hours are due to the penicillin entrappeddeep in the colloidal gel repository site.

As indicated in my experiments, I preferred to use pectin (of all of theexamples I have illustrated as useful here) since it is a readilyavailable naturally occurring substance produced in large quantities.Furthermore, pectin is nontoxic and is readily absorbed by the bodyofiering no difficulty to the tissue enzymes which are responsible forits assimilation in the body. In addition, because of its molecularstructure, it is non-antigenic, i. e., it will not produce antibodiesand thus will not sensitize the body tissues to later contacts with it.

Although, as I have indicated, I prefer a mix with pectin, otherpolysaccharides, cellulose compounds and proteins may be used when theyhave the common characteristic that they form colloidal gels on beingbrought into contact with water. Thus pectin or sodium alginate, bothpolysaccharides, form gels on contact with water and are satisfactorypolysaccharides for use in this invention.

By contrast, sucrose (common table sugar) or lactose (milk sugar) whichare also polysaccharides, do not form gels on contact with water butrather form clear solutions. These types of polysaccharides thereforewould be unsatisfactory in this invention.

Similarly, gelatin, a protein substance, does form a colloidal gel oncontact with water and would be useful in this invention, while casein,the protein of milk, does notform a colloidal gel on contact with waterand so would not be suit able.

Streptomycin ration, I first prepared the pectin by drying it in a hotair oven until the pectin contained less than 1% moisture. The pectin ismilled in a Waring Blendor until it is of proper particle size, 1. e.,

50-100 microns. To mg. of pectin I added .5

gm. of streptomycin calcium chloride trihydrochloride double salt whichas with penicillin had also been dried to contain less than 1% moisture.I mixed this thoroughly and added suiiicient peanut oil to make 1milliliter. The whole was then mixed in a Waring Blendor to make ithomogeneous and placed in glass tubes and sterilized by dry heat at atemperature of 100"-110 C. for eight to ten hours.

As a control I made a preparation of streptomycin and peanut 011 only ina similar manner.

Both of the above preparations were injected intramuscularly in'theright rear legs of rabbits. Blood samples were withdrawn at suitableintervals and the quantity of streptomycin determined 'by the B.subtilis cup plate assay method. The results are shown in the followingTable 3.

TABLE 3 Streptomycin in micrograms per milliliter of serum MaterialInjected 17 Hr. 21 Hr. 24 Hr.

Mycin-PectimoiL. 6.9 1.2 .82 d 10.2 3.3 4.6 do 1.55 .85 .58 d0 7.2 1.55.78 ..-do 1.2 .66 .20

(Averages). (5.41) (1.51) (1.39) Mycin-Oll 1.0 1.85 .46 do .6 .3 .0

I .52 I (0.15), 0.94 (0.26) l l S-39 died following 17 hour bleeding.

It will be noted from the Table 3 that all five rabbits injected withthe pectin preparation had relatively high blood concentrations of thisdrug through the 24th hour. In contrast one of the three rabbitsinjected with the preparation containing no pectin failed to showstreptomycin in the 24th hour. Moreover, the average blood levels withthe pectin preparations were more than seven times higher at the 17thhour, more than 1.5 times higher in the 21st hour and more than timeshigher in the 24th hour than those obtained with preparations which hadno pectin in it.

In the above example I have described preparations and tests of twoantibiotics from molds. Other antibiotic molds or bacterial metabolic orbiological excretory products which can be made in accordance with thisinvention include besides penicillin and streptomycin, penicillin X,penicillin F, penicillin G, penicillin dihydro F, penicillin K, derivedfrom various strains of Penicillium notatum, and Penicilliumchrysogenum; bacitracin, eumycin and subtilin derived from B. subtilisand other similar mold or bacterial excretory products possessingantibiotic properties.

Preferably the mold or bacterial excretory products is in the form of aneutral salt which is highly water soluble, as for example, penicillinpotassium. However, both the molds and the bacterial excretory productsmay be in the form of salts such as penicillin sodium or penicillincalcium, streptomycin sulphate, streptomycin phosphate, streptomycinhydrochloride, streptomycin calcium chloride, trihydrochloride doublesalt, etc.

Drugs such as insulin, epinephrine, ephedrine and hormones, includingestrin, estrdiole and 8 stil-besterol; vitamins such as folic acid,vitamin 'Ei complex, vitamin C (ascorbic acid),.liver extract and drugswhere the therapeutic eilect is prising an oleaginous normally-liquidvehicle having combined therewith a drug which is normally rapidlyassimilated upon injection, and pectin, said composition containing lessthan 1% free water.

2. The composition of claim 1 wherein the oleaginous vehicle is peanutoil.

3. The composition of claim 1 wherein the drug is streptomycin.

4. The composition of claim 1 wherein the drug is a hormone.

5. The composition of claim 1 wherein the oleaginous vehicle ispropylene glycol.

6. An injectable therapeutic composition comprising an oleaginousnormally-liquid vehicle having penicillin and pectin combined therewith,said composition containing less than 1% free water.

7. An injectable therapeutic composition comprising peanut oil havingpenicillin and pectin dispersed therein, said composition containingless than 1% free water, whereby said composition is readily injectablebut upon contact with aqueous body fluids becomes slowly resorbable toyield prolonged medication.

8. The composition of claim 7 wherein each cubic centimeter thereofcontains about milligrams of penicillin and about 270 milligrams ofpectin, the balance being substantially all peanut oil.

HENRY WELCH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name 'Date 67,555 Joly A118. 6, 18671,631,244 Carter June 7, 1927 2,294,016 Brahn Aug. 25, 1942 OTHERREFERENCES Apr. 13, 194s.

